Chip cards presently are used in a variety of applications and comprise a card of approximately the same size as a standard credit card. The card, itself, contains intelligence in the form of a memory circuit. A card reader or card connector is used to detect certain information stored on the card, and is used in applications such as banking machines, cable television decoders or descramblers, and a variety of other uses.
One type of chip card is identified as a "Subscriber's Identification Module" or "SIM" card which is a miniature chip card for use in small hand held devices such as pocket size cellular telephones. The SIM provides user identification in individual telephone handsets and the SIM card reader readily accommodates insertion and removal of the SIM to provide quick identification and easy access by a cellular telephone user.
A typical SIM or other chip card has exposed contact pads for matingly engaging underlying cantilevered contacts of a SIM connector or card reader. Since the card is inserted and removed manually, SIM connectors have had some inherent design difficulties.
One such difficulty in the use of chip cards and their respective readers involves contamination of the exposed contacts which can disintegrate the integrity and reliability of the electrical connection between the card and the underlying contacts. Since chip cards are typically carried by a person and are exposed to a wide range of contaminants, the card reader is exposed to all kinds of dirt or contaminants, particularly with mobile cellular telephone applications or automatic teller machines which involve outdoor use.
Another design difficulty in chip card readers involves the incorporation of means to detect the presence of the card into the card reader. Such detect means signals that the card is fully seated, and are typically in the form of end position or end-of-stroke switches incorported into the card reader to detect complete insertion of the card. These end position switches can be either normally open switches or normally closed switches. When a change in state of the switch is detected, such as if the card is in its completely inserted position, the card reader is activated and data is transmitted from (or to) the chip card.
Because of the portable nature of chip cards and their respective readers and their known exposure to contaminants, known prior art connectors incorporating switches have used expensive and sometimes complicated designs to protect against contaminants and damage and to ensure the integrity and reliability of the system. There is therefore a need for a simple, yet reliable and economic switch design to incorporate in a chip card or SIM reader or connector. The present invention is directed to satisfying this need and solving the various problems discussed above.